src/hb-ot-shape.cc

   1 /*
   2  * Copyright © 2009,2010  Red Hat, Inc.
   3  * Copyright © 2010  Google, Inc.
   4  *
   5  *  This is part of HarfBuzz, a text shaping library.
   6  *
   7  * Permission is hereby granted, without written agreement and without
   8  * license or royalty fees, to use, copy, modify, and distribute this
   9  * software and its documentation for any purpose, provided that the
  10  * above copyright notice and the following two paragraphs appear in
  11  * all copies of this software.
  12  *
  13  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
  14  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
  15  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
  16  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
  17  * DAMAGE.
  18  *
  19  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
  20  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
  21  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
  22  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
  23  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  24  *
  25  * Red Hat Author(s): Behdad Esfahbod
  26  * Google Author(s): Behdad Esfahbod
  27  */
  28
  29 #include "hb-ot-shape-private.hh"
  30 #include "hb-ot-shape-complex-private.hh"
  31
  32 #include "hb-font-private.hh"
  33
  34 HB_BEGIN_DECLS
  35
  36
  37 /* XXX vertical */
  38 hb_tag_t default_features[] = {
  39   HB_TAG('c','a','l','t'),
  40   HB_TAG('c','c','m','p'),
  41   HB_TAG('c','l','i','g'),
  42   HB_TAG('c','u','r','s'),
  43   HB_TAG('k','e','r','n'),
  44   HB_TAG('l','i','g','a'),
  45   HB_TAG('l','o','c','l'),
  46   HB_TAG('m','a','r','k'),
  47   HB_TAG('m','k','m','k'),
  48   HB_TAG('r','l','i','g')
  49 };
  50
  51 static void
  52 hb_ot_shape_collect_features (hb_ot_shape_plan_t       *plan,
  53                               const hb_segment_properties_t  *props,
  54                               const hb_feature_t       *user_features,
  55                               unsigned int              num_user_features)
  56 {
  57   switch (props->direction) {
  58     case HB_DIRECTION_LTR:
  59       plan->map.add_bool_feature (HB_TAG ('l','t','r','a'));
  60       plan->map.add_bool_feature (HB_TAG ('l','t','r','m'));
  61       break;
  62     case HB_DIRECTION_RTL:
  63       plan->map.add_bool_feature (HB_TAG ('r','t','l','a'));
  64       plan->map.add_bool_feature (HB_TAG ('r','t','l','m'), false);
  65       break;
  66     case HB_DIRECTION_TTB:
  67     case HB_DIRECTION_BTT:
  68     case HB_DIRECTION_INVALID:
  69     default:
  70       break;
  71   }
  72
  73   for (unsigned int i = 0; i < ARRAY_LENGTH (default_features); i++)
  74     plan->map.add_bool_feature (default_features[i]);
  75
  76   hb_ot_shape_complex_collect_features (plan, props);
  77
  78   for (unsigned int i = 0; i < num_user_features; i++) {
  79     const hb_feature_t *feature = &user_features[i];
  80     plan->map.add_feature (feature->tag, feature->value, (feature->start == 0 && feature->end == (unsigned int) -1));
  81   }
  82 }
  83
  84
  85 static void
  86 hb_ot_shape_setup_masks (hb_ot_shape_context_t *c)
  87 {
  88   hb_mask_t global_mask = c->plan->map.get_global_mask ();
  89   c->buffer->reset_masks (global_mask);
  90
  91   hb_ot_shape_complex_setup_masks (c); /* BUFFER: Clobbers var2 */
  92
  93   for (unsigned int i = 0; i < c->num_user_features; i++)
  94   {
  95     const hb_feature_t *feature = &c->user_features[i];
  96     if (!(feature->start == 0 && feature->end == (unsigned int)-1)) {
  97       unsigned int shift;
  98       hb_mask_t mask = c->plan->map.get_mask (feature->tag, &shift);
  99       c->buffer->set_masks (feature->value << shift, mask, feature->start, feature->end);
 100     }
 101   }
 102 }
 103
 104
 105 static void
 106 hb_ot_substitute_complex (hb_ot_shape_context_t *c)
 107 {
 108   if (!hb_ot_layout_has_substitution (c->face))
 109     return;
 110
 111   c->plan->map.substitute (c->face, c->buffer);
 112
 113   c->applied_substitute_complex = TRUE;
 114   return;
 115 }
 116
 117 static void
 118 hb_ot_position_complex (hb_ot_shape_context_t *c)
 119 {
 120
 121   if (!hb_ot_layout_has_positioning (c->face))
 122     return;
 123
 124   unsigned int count = c->buffer->len;
 125   for (unsigned int i = 0; i < count; i++) {
 126     hb_font_add_glyph_origin_for_direction (c->font, c->buffer->info[i].codepoint,
 127                                             HB_DIRECTION_LTR,
 128                                             &c->buffer->pos[i].x_offset,
 129                                             &c->buffer->pos[i].y_offset);
 130   }
 131
 132   c->plan->map.position (c->font, c->face, c->buffer);
 133
 134   for (unsigned int i = 0; i < count; i++) {
 135     hb_font_subtract_glyph_origin_for_direction (c->font, c->buffer->info[i].codepoint,
 136                                                  HB_DIRECTION_LTR,
 137                                                  &c->buffer->pos[i].x_offset,
 138                                                  &c->buffer->pos[i].y_offset);
 139   }
 140
 141   hb_ot_layout_position_finish (c->buffer);
 142
 143   c->applied_position_complex = TRUE;
 144   return;
 145 }
 146
 147
 148 /* Main shaper */
 149
 150 /* Prepare */
 151
 152 static inline hb_bool_t
 153 is_variation_selector (hb_codepoint_t unicode)
 154 {
 155   return unlikely ((unicode >=  0x180B && unicode <=  0x180D) || /* MONGOLIAN FREE VARIATION SELECTOR ONE..THREE */
 156                    (unicode >=  0xFE00 && unicode <=  0xFE0F) || /* VARIATION SELECTOR-1..16 */
 157                    (unicode >= 0xE0100 && unicode <= 0xE01EF));  /* VARIATION SELECTOR-17..256 */
 158 }
 159
 160 static void
 161 hb_set_unicode_props (hb_ot_shape_context_t *c)
 162 {
 163   hb_unicode_funcs_t *unicode = c->buffer->unicode;
 164   hb_glyph_info_t *info = c->buffer->info;
 165
 166   unsigned int count = c->buffer->len;
 167   for (unsigned int i = 1; i < count; i++) {
 168     info[i].general_category() = unicode->get_general_category (info[i].codepoint);
 169     info[i].combining_class() = unicode->get_combining_class (info[i].codepoint);
 170   }
 171 }
 172
 173 static void
 174 hb_form_clusters (hb_ot_shape_context_t *c)
 175 {
 176   unsigned int count = c->buffer->len;
 177   for (unsigned int i = 1; i < count; i++)
 178     if (c->buffer->info[i].general_category() == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)
 179       c->buffer->info[i].cluster = c->buffer->info[i - 1].cluster;
 180 }
 181
 182 static void
 183 hb_ensure_native_direction (hb_ot_shape_context_t *c)
 184 {
 185   hb_direction_t direction = c->buffer->props.direction;
 186
 187   /* TODO vertical:
 188    * The only BTT vertical script is Ogham, but it's not clear to me whether OpenType
 189    * Ogham fonts are supposed to be implemented BTT or not.  Need to research that
 190    * first. */
 191   if ((HB_DIRECTION_IS_HORIZONTAL (direction) && direction != hb_script_get_horizontal_direction (c->buffer->props.script)) ||
 192       (HB_DIRECTION_IS_VERTICAL   (direction) && direction != HB_DIRECTION_TTB))
 193   {
 194     hb_buffer_reverse_clusters (c->buffer);
 195     c->buffer->props.direction = HB_DIRECTION_REVERSE (c->buffer->props.direction);
 196   }
 197 }
 198
 199 static void
 200 hb_reset_glyph_infos (hb_ot_shape_context_t *c)
 201 {
 202   unsigned int count = c->buffer->len;
 203   for (unsigned int i = 0; i < count; i++)
 204     c->buffer->info[i].var1.u32 = c->buffer->info[i].var2.u32 = 0;
 205 }
 206
 207
 208 /* Substitute */
 209
 210 static void
 211 hb_mirror_chars (hb_ot_shape_context_t *c)
 212 {
 213   hb_unicode_funcs_t *unicode = c->buffer->unicode;
 214
 215   if (HB_DIRECTION_IS_FORWARD (c->target_direction))
 216     return;
 217
 218   hb_mask_t rtlm_mask = c->plan->map.get_1_mask (HB_TAG ('r','t','l','m'));
 219
 220   unsigned int count = c->buffer->len;
 221   for (unsigned int i = 0; i < count; i++) {
 222     hb_codepoint_t codepoint = unicode->get_mirroring (c->buffer->info[i].codepoint);
 223     if (likely (codepoint == c->buffer->info[i].codepoint))
 224       c->buffer->info[i].mask |= rtlm_mask; /* XXX this should be moved to before setting user-feature masks */
 225     else
 226       c->buffer->info[i].codepoint = codepoint;
 227   }
 228 }
 229
 230 static void
 231 hb_map_glyphs (hb_font_t    *font,
 232                hb_buffer_t  *buffer)
 233 {
 234   if (unlikely (!buffer->len))
 235     return;
 236
 237   hb_codepoint_t glyph;
 238   buffer->clear_output ();
 239   unsigned int count = buffer->len - 1;
 240   for (buffer->i = 0; buffer->i < count;) {
 241     if (unlikely (is_variation_selector (buffer->info[buffer->i + 1].codepoint))) {
 242       hb_font_get_glyph (font, buffer->info[buffer->i].codepoint, buffer->info[buffer->i + 1].codepoint, &glyph);
 243       buffer->replace_glyph (glyph);
 244       buffer->i++;
 245     } else {
 246       hb_font_get_glyph (font, buffer->info[buffer->i].codepoint, 0, &glyph);
 247       buffer->replace_glyph (glyph);
 248     }
 249   }
 250   if (likely (buffer->i < buffer->len)) {
 251     hb_font_get_glyph (font, buffer->info[buffer->i].codepoint, 0, &glyph);
 252     buffer->replace_glyph (glyph);
 253   }
 254   buffer->swap ();
 255 }
 256
 257 static void
 258 hb_substitute_default (hb_ot_shape_context_t *c)
 259 {
 260   hb_map_glyphs (c->font, c->buffer);
 261 }
 262
 263 static void
 264 hb_substitute_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
 265 {
 266   /* TODO Arabic */
 267 }
 268
 269
 270 /* Position */
 271
 272 static void
 273 hb_position_default (hb_ot_shape_context_t *c)
 274 {
 275   hb_ot_layout_position_start (c->buffer);
 276
 277   unsigned int count = c->buffer->len;
 278   for (unsigned int i = 0; i < count; i++) {
 279     hb_font_get_glyph_advance_for_direction (c->font, c->buffer->info[i].codepoint,
 280                                              c->buffer->props.direction,
 281                                              &c->buffer->pos[i].x_advance,
 282                                              &c->buffer->pos[i].y_advance);
 283     hb_font_subtract_glyph_origin_for_direction (c->font, c->buffer->info[i].codepoint,
 284                                                  c->buffer->props.direction,
 285                                                  &c->buffer->pos[i].x_offset,
 286                                                  &c->buffer->pos[i].y_offset);
 287   }
 288 }
 289
 290 static void
 291 hb_position_complex_fallback (hb_ot_shape_context_t *c HB_UNUSED)
 292 {
 293   /* TODO Mark pos */
 294 }
 295
 296 static void
 297 hb_truetype_kern (hb_ot_shape_context_t *c)
 298 {
 299   /* TODO Check for kern=0 */
 300   unsigned int count = c->buffer->len;
 301   for (unsigned int i = 1; i < count; i++) {
 302     hb_position_t x_kern, y_kern, kern1, kern2;
 303     hb_font_get_glyph_kerning_for_direction (c->font,
 304                                              c->buffer->info[i - 1].codepoint, c->buffer->info[i].codepoint,
 305                                              c->buffer->props.direction,
 306                                              &x_kern, &y_kern);
 307
 308     kern1 = x_kern >> 1;
 309     kern2 = x_kern - kern1;
 310     c->buffer->pos[i - 1].x_advance += kern1;
 311     c->buffer->pos[i].x_advance += kern2;
 312     c->buffer->pos[i].x_offset += kern2;
 313
 314     kern1 = y_kern >> 1;
 315     kern2 = y_kern - kern1;
 316     c->buffer->pos[i - 1].y_advance += kern1;
 317     c->buffer->pos[i].y_advance += kern2;
 318     c->buffer->pos[i].y_offset += kern2;
 319   }
 320 }
 321
 322 static void
 323 hb_position_complex_fallback_visual (hb_ot_shape_context_t *c)
 324 {
 325   hb_truetype_kern (c);
 326 }
 327
 328
 329 /* Do it! */
 330
 331 static void
 332 hb_ot_shape_execute_internal (hb_ot_shape_context_t *c)
 333 {
 334   /* Save the original direction, we use it later. */
 335   c->target_direction = c->buffer->props.direction;
 336
 337   hb_reset_glyph_infos (c); /* BUFFER: Clear buffer var1 and var2 */
 338
 339   hb_set_unicode_props (c); /* BUFFER: Set general_category and combining_class in var1 */
 340
 341   hb_ensure_native_direction (c);
 342
 343   hb_form_clusters (c);
 344
 345   hb_ot_shape_setup_masks (c); /* BUFFER: Clobbers var2 */
 346
 347   /* SUBSTITUTE */
 348   {
 349     /* Mirroring needs to see the original direction */
 350     hb_mirror_chars (c);
 351
 352     hb_substitute_default (c);
 353
 354     hb_ot_substitute_complex (c);
 355
 356     if (!c->applied_substitute_complex)
 357       hb_substitute_complex_fallback (c);
 358   }
 359
 360   /* POSITION */
 361   {
 362     hb_position_default (c);
 363
 364     hb_ot_position_complex (c);
 365
 366     hb_bool_t position_fallback = !c->applied_position_complex;
 367     if (position_fallback)
 368       hb_position_complex_fallback (c);
 369
 370     if (HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction))
 371       hb_buffer_reverse (c->buffer);
 372
 373     if (position_fallback)
 374       hb_position_complex_fallback_visual (c);
 375   }
 376
 377   c->buffer->props.direction = c->target_direction;
 378 }
 379
 380 static void
 381 hb_ot_shape_plan_internal (hb_ot_shape_plan_t       *plan,
 382                            hb_face_t                *face,
 383                            const hb_segment_properties_t  *props,
 384                            const hb_feature_t       *user_features,
 385                            unsigned int              num_user_features)
 386 {
 387   plan->shaper = hb_ot_shape_complex_categorize (props);
 388
 389   hb_ot_shape_collect_features (plan, props, user_features, num_user_features);
 390
 391   plan->map.compile (face, props);
 392 }
 393
 394 static void
 395 hb_ot_shape_execute (hb_ot_shape_plan_t *plan,
 396                      hb_font_t          *font,
 397                      hb_buffer_t        *buffer,
 398                      const hb_feature_t *user_features,
 399                      unsigned int        num_user_features)
 400 {
 401   hb_ot_shape_context_t c = {plan, font, font->face, buffer, user_features, num_user_features};
 402   hb_ot_shape_execute_internal (&c);
 403 }
 404
 405 void
 406 hb_ot_shape (hb_font_t          *font,
 407              hb_buffer_t        *buffer,
 408              const hb_feature_t *features,
 409              unsigned int        num_features)
 410 {
 411   hb_ot_shape_plan_t plan;
 412
 413   hb_ot_shape_plan_internal (&plan, font->face, &buffer->props, features, num_features);
 414   hb_ot_shape_execute (&plan, font, buffer, features, num_features);
 415 }
 416
 417
 418 HB_END_DECLS